The present invention relates generally to an apparatus and method for hardening metal using irradiation and alternate heating.
The effects of radiation on metals, especially from nuclear reactors, have been studied and reported for many years. Most of these studies have focused on the effects of nuclear radiation on nuclear reactor pressure vessels and other metal components in and around the core of a nuclear power plant. However, almost all of the previous work on the effects of nuclear radiation on metal focused on the deleterious changes induced in the metal, particularly the embrittling effect of nuclear radiation on metal.
Less abundant in the prior reports is the effect of electron radiation on metals. For example, a study by M. J. Mankin, A. T. Churchman, D. R. Harries, and R. E. Smallman showed that high doses of electron radiation can affect specific structural properties of metal, such as critical shear stress. However, the focus of this study was also on the deleterious effects of the radiation on the metal.
Data on the useful application of radiation is nearly non-existent. Recent publications by V. J. Jabotinsid described the useful application of highdose electron beam radiation on tungsten carbide and other hard metals. As seen in FIG. 2, Jabotinski used an electron beam generator to both irradiate and heat the metal.
Jabotinski""s process called for the electron beam treatment of the metal sample with 1.4 MeV electrons. The metal samples were kept in the air under a melting medium or xe2x80x9cgatexe2x80x9d. In his experiments, Jabotinski exclusively used electron beams to both radiate and heat metal in a liquid gate. As such, Jabotinski failed to use auxiliary heating to efficiently and effectively maintain conditions conducive to the facilitation of the morphological changes in the metal.
Jabotinski failed to produce a useful commercial product because the yield is low and is uneconomical for most industrial applications. For example, Jabotinski""s work used 1.4 MeV electrons that are largely stopped in the gate material and, as a result, never reach the metal sample. Most of the electron radiation failed to reach the sample because normally 1.4 MeV electrons penetrate to only an approximate depth of only 2.6 mm in a typical oxide gate with a density of 2.7 g/cc. As a result, almost no electron radiation reached the metal sample and the limited amount that does only penetrated to a depth of less than a micron into the surface of the metal sample.
Other minute amounts of radiation from the electron beam may reach the metal sample. It is well known in the art that an energy beam creates x-rays when the energy beam strikes a solid object and releases photons. Since the electron beams in Jabotinski""s work are stopped in the oxide gate, less than one tenth of one percent of the electron radiation could be converted into x-rays, which could penetrate the melted oxide gate and reach the metal sample. This percentage is extreme low and practically insignificant in the irradiation of the metal.
Another draw back to Jabotinski""s work is the lack of an alternative heating source. Jabotinski exclusively used the electron radiation deposited into the gate material to heat the gate and the metal sample. This is an extremely expensive technique for heating. Also, Jabotinski""s work only described a process where the heating and irradiation are performed simultaneously by the radiation. As a result, Jabotinsid""s work lacks efficiency and is uneconomical for most industrial applications.
Thus, there is a need for an apparatus and method that effectively, economically, and efficiently hardens metal through irradiation.
The present invention provides an apparatus for hardening a metal article, comprising a holding device, an energy beam generator pointed at the holding device for directing energy beams at the holding device, and an auxiliary heating device engaging the holding device, wherein the auxiliary heating device heats the metal article independently from the energy beam. The apparatus includes an energy beam delivery instrument system positioned between the energy beam generator and the holding device so that the energy an energy beam delivery instrument directs the energy beam to the holding device. Also, the apparatus also includes a transport system supporting the holding device, wherein the transport system varies the location of the holding device relative to the energy beam generator.
A method for hardening metal is also disclosed. This method includes irradiating the metal and heating the metal independently from the irradiation. The method teaches separating the metal from the atmosphere using a fluid material, irradiating the metal in intervals, cycling the metal through the irradiation, and converting an energy beam into x-rays.
A main purpose of this invention is to effectively, economically, and efficiently harden metal by irradiating the metal article with an energy beam. This purpose requires heating and irradiating the metal sample with predetermined amounts of irradiation at a predetermined temperature to foster the metallurgical changes within the metal sample.
Irradiation of the metal samples causes a reduction in the porosity of the metal surface. Also, the irradiation creates a monolithic surface structure where the components of the metal sample, tungsten carbide and a cobalt binder, are converted into new phases. These two phenomenons facilitate increase in the wear characteristic of the metal sample.
It is therefore a general objective of the present invention to provide an apparatus for hardening metal using irradiation.
Another objective of the present invention is to provide an apparatus for hardening metal using irradiation and heat independent from the irradiation.
Still another objective of this invention is to harden metal by purposefully converting an energy beam into x-rays in order to increase the amount of radiation reaching the metal.
Yet another objective of the present invention is the use of gamma rays to harden metal.
Another object of the present invention is to reduce the amount of irradiation needed to harden metal by using higher energy irradiation.
Still yet another objective of the present invention is to harden tungsten carbide through irradiation.
Still another objective of the present invention is to harden metal through the application of irradiation to the metal while the metal cycles in and out of the irradiation.
Yet another objective of the present invention is the disclosure of methods for hardening metal by irradiating the metal and heating the metal independently from the irradiation.
Still yet another objective of the present invention is the disclosure of methods for hardening metal by irradiating the metal and transporting the metal through the irradiation.
Numerous other objects, features and advantages of the present invention will be readily apparent to those skilled in the art, upon the reading of the following disclosure, when taken in conjunction with the new drawings.